Air conditioning systems capable of adjusting the humidity as well as the temperature of an object space have been known previously. For example, Japanese Laid-open Patent Application 2010-243005 has disclosed an air conditioning system set up in a semiconductor factory or the like. This air conditioning system cools air supplied indoors in an air conditioning unit by a cooling heat exchanger through which cold water supplied by a chiller unit circulates as a heat exchanging medium, and cools and dehumidifies the air. This air conditioning system can also heat air by an electric heater and humidify air by a sprinkler to adjust the temperature and the humidity by a combination of cooling, dehumidification, heating, and humidification.